In general, large commercial vehicles, such as buses and the like, employ a sliding door device to allow passengers to easily get on or get off.
The sliding door device includes a sliding door moving along a guiding rail provided in a vehicle in order to open and close a door opening formed in the vehicle. A pneumatic cylinder is a power source for moving the sliding door, and a microswitch senses closing of the sliding door. A controller is configured to control the pneumatic cylinder on the basis of a sensing signal from the microswitch to control an opening and closing operation of the sliding door.
The sliding door device also implements a sliding door safe closing function to prevent damaging an object or injuring a passenger when the object or the passenger is caught in a space between the sliding door and the door opening during a door closing operation in which the sliding door blocks the door opening.
When the object or passenger is caught in the space between the sliding door and the door opening while the sliding door is being closed, the sliding door safety closing function moves the sliding door in a reverse direction, i.e., in a direction in which the door opening is opened, thus preventing an object or a passenger from being caught.
The object or passenger caught in the sliding door is sensed by a pressure change within a door weather strip attached to cushion impact applied to the sliding door and secure airtightness. When the object or passenger is caught, a pressure is applied to the door weather strip to change the internal pressure, and such a change in the internal pressure of the door weather strip is sensed by a pressure switch so as to determine whether the object or passenger is caught.
However, in the related art, when the sliding door is closed, although objects such as the clothes of a passenger, bag straps, or the like, or a body part of a passenger is caught in the sliding door, they are disregarded in a certain section immediately before the sliding door is completely closed, e.g., in a section up to 30 mm wide immediately before the sliding door is completely closed. The closing operation of the sliding door continues in order to prevent malfunction due to compression of the door weather strip, thereby damaging the object or inflicting an injury on the passenger.
On a downhill slop, the sliding door is first closed by its own weight before the microswitch senses closing of the sliding door, generating a misdetection situation in which the microswitch cannot properly sense the closing of the sliding door. In order to prevent this, a point in time at which closing of the sliding door is recognized through the microswitch is set to be ahead of a predetermined interval, e.g., 30 mm from a point in time at which door is completely closed.
During the interval of 30 mm immediately before the sliding door is completely closed, although the object, such as the clothes of the passenger and the bag strap, or a body part of the passenger is caught in the sliding door, the closing operation of the sliding door continues and damages the object or inflicts an injury on the passenger.
When sensing the objects or the passenger caught in the sliding door, the internal pressure of the door weather strip may change according to a change in ambient temperature which causes a malfunction. Thus, the object or the passenger is determined to be caught only when the internal pressure of the door weather strip is equal to or higher than a predetermined pressure, e.g., 4.5 kgf.
A relatively small object having a size of, for example, 30×60 mm or less in thickness and width, or a small body part of a passenger is caught in the sliding door, would not be sensed due to low pressure, and thus, the closing operation of the sliding door continues and damages the object or inflicts injury on the passenger. Further, if the vehicle is running with the passenger caught in the sliding door, an accident may occur.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.